The efficacy and tolerability of high dose simvastatin therapy in patients with NIDDM has not been evaluated. In this investigation, it is planned to study the maximum reduction in fasting plasma triglyceride concentrations and VLDL remnants in patients with NIDDM who have borderline or moderate hypertriglyceridemia with high LDL cholesterol levels. The study will compare simvastatin therapy (80 mg once daily) with identical placebo for lipid and lipoprotein response in 10 NIDDM patients with hypertriglyceridemia.